The influence of annealing on the microstructure and mechanical properties of beta-form isotactic polypropylene (iPP) was investigated via in situ synchrotron small-angle X-ray scattering (SAXS), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC). Transition of beta-iPP to alpha-iPP was investigated via recrystallization at high annealing temperatures (T (a) > 120 A degrees C). And crystallinity, crystal sizes, and long period of ordered structure increased with increasing annealing temperature. Abrupt changes were found in both mechanical properties and structural features at the same T (a) range (similar to 120 A degrees C). The in situ synchrotron SAXS and WAXD shows that the destruction of b phase at yielding and after yielding should account for the ductility of beta-iPP. The thermodynamics and kinetics of annealing were investigated with DSC and X-ray synchrotron experiments. A characteristic annealing time was investigated, which measures the rate of phase evolution in annealing of beta-iPP. Eventually, a hypothesized model can be used to describe the property/structure relations during this process.
Shang, YR,Zhao, J,Li, JQ,et al. Investigations in annealing effects on structure and properties of beta-isotactic polypropylene with X-ray synchrotron experiments[J]. COLLOID AND POLYMER SCIENCE,2014,292(12):3205-3221.
Shang, YR,Zhao, J,Li, JQ,Wu, ZH,&Jiang, SC；吴忠华.(2014).Investigations in annealing effects on structure and properties of beta-isotactic polypropylene with X-ray synchrotron experiments.COLLOID AND POLYMER SCIENCE,292(12),3205-3221.
Shang, YR,et al."Investigations in annealing effects on structure and properties of beta-isotactic polypropylene with X-ray synchrotron experiments".COLLOID AND POLYMER SCIENCE 292.12(2014):3205-3221.